The present invention relates to an image fusion processing method, image fusion processing program, and image fusion processing device. More specifically, the present invention relates to an image fusion processing method, image fusion processing program, and image fusion processing device for fusing a plurality of images of three or more dimensions obtained from a single watched object without degenerating the amount of information.
Heretofore, diagnosis in the medical field has been accomplished through the aid of imaging a single watched object, such as an organ in a human body, using a plurality of different modalities, including computerized tomography (CT) imaging devices, positron emission tomography (PET) imaging devices and the like, and fusing the plurality of images obtained by these plurality of imaging apparatuses so as to use the fusion image for diagnosis. For example, the sizes and positional relationships of lesions can be precisely recognized by fusing a high resolution CT image and a PET image showing organ function information.
FIG. 1 shows one conventional process for fusing a plurality of such images. In the process of FIG. 1, a plurality of volume data (CT image 101, PET image 103) separately undergo rendering, then the respective images 105 and 107 are fused at a fixed ratio to generate a fusion image 109. However, since a plurality of images are synthesized two-dimensionally in this process, the contours accurately represented in the CT image and the color of the watched object in the fusion image 109 are both blurred.
FIG. 2 shows another conventional process for fusing a plurality of images. In the process of FIG. 2, a plurality of voxel values are synthesized for each predetermined sampling point. Then, the synthesized voxel value 111 is rendered to generate a fusion image 113 (refer to, for example, Maria Ferre, Anna Puig, Dani Tost, “A framework for fusion methods and rendering techniques of multimodal volume data”, Journal of Visualization and Computer Animation 15(2): 63-77 (2004)). The thus obtained fusion image 113 is sharp, and the anterior-posterior relationship is accurately represented.
However, since a plurality of voxel values are synthesized prior to rendering in this image fusion process, all of the optical parameters obtained from volume data, such as opacity, shading coefficient, color and the like, are dependent on the synthesized voxel value. Therefore, the multi-dimensional information included in the plurality of volume data degenerates in one dimensional information in the synthesized voxel value. That is, the representation of the fused image is limited since the optical parameters of either the CT image or PET image are used for the rendering. Especially, the fusion image is unnatural when the CT image and the PET image have different resolutions.